There are many types of topical antiperspirant products that are commercially available or otherwise known in the antiperspirant art. Most of these products are formulated as roll-on liquids, creams, emulsions, gels, gel-solids, or other solid stick formulations, and comprise an antiperspirant active and gellant incorporated into a suitable liquid carrier. These products are designed to provide effective perspiration and odor control while also being cosmetically acceptable during and after application onto the axillary area or other areas of the skin.
Many of these antiperspirant products comprising a gellant and liquid carrier are formulated at high processing temperature to solubilize the gellant in the liquid carrier. Typically, the gellant and other components except the antiperspirant active are added to a suitable liquid carrier and the solution is heated to a selected processing temperature to dissolve the gellant. Depending on the melting point of the selected gellant, the processing temperature can be increased or longer processing times used, but this can result in increased processing costs and lower gellant stability. Because it can be difficult to form a liquid solution of gellant and liquid carrier at the selected processing temperature, processing aids such as coupling agents are typically included in the formulation. It is well known that cosmetic emollients, e.g,. aliphatic fatty alcohols, are generally used as coupling agents in antiperspirant compositions to improve solubilization of the selected gellants and provide for a liquid solution of gellant and liquid carrier at the selected processing temperature, especially when the liquid carrier included in the composition contains a non-polar volatile silicone material.
Aliphatic fatty alcohols such as octyldodecanols are common cosmetic emollients that are particularly useful as coupling agents in anhydrous antiperspirant compositions because these solvents are readily soluble in non-polar volatile silicones and help to solubilize the gellant included in the composition. These particular coupling agents can also provide for the use of an increased amount of the volatile silicone oil, and the use of volatile silicone oils in antiperspirant compositions can provide highly desirable aesthetics benefits such as dry feel when the composition is applied to the skin. It has been found, however, that the use of some aliphatic fatty alcohols including octyldodecanol can interfere with antiperspirant efficacy and/or tend to feel greasy and sticky on the skin even when the aliphatic fatty alcohol is used in combination with a dry feeling solvent such as a volatile silicone.
It has now been found that a combination of a polar aliphatic alcohol, specifically hexylene glycol, and a hydrocarbon oil can be included in anhydrous antiperspirant compositions to improve coupling of the selected gellant with a volatile silicone liquid carrier. This select coupling agent combination is effective even at lower coupler concentrations, and helps to minimize the use of high concentrations of other emollient couplers which can interfere with antiperspirant efficacy and/or produce undesirable cosmetic aesthetics.
It has been surprisingly found that a solution of hexylene glycol, hydrocarbon oil, and a volatile silicone liquid carrier can result in a homogenous liquid mixture. This is surprising given that hexylene glycol is not miscible when used alone in combination with a hydrocarbon oil or a volatile silicone liquid carrier. It has been discovered, however, that the use of a select combination of hexylene glycol and a hydrocarbon oil at a certain weight ratio can provide not only homogenous liquid solutions of volatile silicone liquid carrier, hexylene glycol and a hydrocarbon oil, but can also provide improved coupling of the liquid carrier with the selected gellant.
It is therefore an object of the present invention to provide an antiperspirant composition which has good antiperspirant and aesthetic performance, and which contains a coupling agent comprising a select combination of hexylene glycol and a hydrocarbon oil. It is a further object of the present invention to provide an antiperspirant composition which contains a coupling agent that provides for improved coupling benefits.